The present invention relates to steam boilers of a type known as "package boilers" that are completely manufactured and assembled in a shop and thereafter transported as a unit to be installed at a given plant site. A burner unit is provided at each of opposite ends thereof to significantly increase the capacity of a coal fired unit.
An important disadvantage of shop built and assembled boilers is that such apparatus is limited in size by the carrying capacity of the railway carrier by which it is delivered to its place of use. Such limitations are imposed upon the apparatus chiefly by railroad clearances encountered along the route of transit. Inasmuch as package boilers are thus limited in size, their capacity is similarly limited, and by necessity they have been effectively limited to the use of highly efficient fuels such as gas or oil.